Just installed the server on Ubuntu server which is working here is how to setup the Djava.awt.headless=true where to put it in the java command for anyone having issues maybe putting it in the wrong place
java -Djava.awt.headless=true -jar /home/Blynk/server-0.19.2.jar -dataFolder /home/Blynk -serverConfig /home/Blynk/server.properties &